1. Field of the Invention
This specification relates to a system for charging a battery of an energy storage system using a photovoltaic inverter (power conditioning system: PCS), and more particularly, to a system for charging a battery of an energy storage system using a photovoltaic inverter, capable of charging energy generated from a single-phase photovoltaic inverter, to a battery of a single-phase energy storage system.
2. Background of the Invention
A single-phase photovoltaic inverter (power conditioning system: PCS) indicates equipment for generating electricity by converting DC energy supplied from a photovoltaic module, into AC energy. And a single-phase energy storage system (ESS) indicates equipment for converting DC energy charged to a battery into AC energy, and then supplying the AC energy to a load.
The single-phase photovoltaic inverter and the single-phase ESS have something in common, in that they convert DC energy into AC energy, and they are configured as a single-phase. However, the single-phase photovoltaic inverter and the single-phase ESS may be differentiated from each other, according to whether DC energy is supplied from a photovoltaic module or a battery.
The single-phase ESS using a battery should charge the battery when the battery is discharged. In the conventional art, the battery was charged with power supplied from a system. However, the battery of the single-phase ESS may be charged with energy generated from a single-phase photovoltaic inverter.
In this case, if the single-phase photovoltaic inverter supplies a smaller amount of energy than a required amount of energy by the single-phase ESS, the single-phase ESS may not smoothly perform a charging operation. Further, the single-phase photovoltaic inverter may be stopped or damaged due to an over-load.
Therefore, the single-phase ESS should be always informed of the amount of energy generated from the single-phase photovoltaic inverter.
However, an output power (the amount of generated energy) of the single-phase photovoltaic inverter is supplied from a photovoltaic module, and the photovoltaic module generates energy according to the amount of solar radiation. Thus, if the amount of solar radiation is changed, an output power of the single-phase photovoltaic inverter is also changed. This may cause energy charged to the single-phase ESS, to be changed according to the amount of solar radiation.
Therefore, it is required for the single-phase ESS to check change of an output power of the single-phase photovoltaic inverter according to the amount of solar radiation.
FIG. 1 is a block diagram illustrating a system for charging a battery of an energy storage system using a PCS in accordance with the conventional art.
Referring to FIG. 1, the conventional system 10 for charging a battery of an energy storage system using a PCS may include a photovoltaic module 11, a single-phase photovoltaic inverter 12, a single-phase energy storage system (ESS) 13, and a load unit 14.
The single-phase ESS 13 may receive information on the amount of an output power of the single-phase photovoltaic inverter 12 according to the amount of solar radiation, using a communication line 15, in order to check that an output power of the single-phase photovoltaic inverter 12 by photovoltaic energy generated from the photovoltaic module 11 is changed according to the amount of solar radiation.
However, the conventional system 10 using such a communication line may have the following disadvantages. Firstly, the single-phase photovoltaic inverter 12 and the single-phase ESS 13 should have the same software related to communication, since communication protocols thereof should be identical to each other. Further, the single-phase photovoltaic inverter 12 and the single-phase ESS 13 should have the same hardware related to communication, by having communication cables and RX/TX lines of ports identical to each other. In a case where a single-phase photovoltaic inverter manufactured from ‘A’ company and a single-phase ESS manufactured from ‘B’ company are used, if software and hardware of the single-phase photovoltaic inverter are different from software and hardware of the single-phase ESS, the system 10 shown in FIG. 1 cannot be implemented.
FIG. 2 is a block diagram illustrating a system for charging a battery of an energy storage system (ESS) using a PCS in accordance with the conventional art.
Referring to FIG. 2, the conventional system 20 for charging a battery of an energy storage system (ESS) using a PCS may include a photovoltaic module 21, a single-phase photovoltaic inverter 22, a single-phase energy storage system (ESS) 23, a load unit 24, and an EMS 25.
The single-phase ESS 23 may receive information on the amount of an output power of the single-phase photovoltaic inverter 22 according to the amount of solar radiation, using a communication line 15, from the EMS 25 or a controller, in order to check that an output power of the single-phase photovoltaic inverter 22 by photovoltaic energy generated from the photovoltaic module 21 is changed according to the amount of solar radiation.
The conventional system 20 has an advantage that a battery of the single-phase ESS 23 can be smoothly charged with respect to change of an output power of the single-phase photovoltaic inverter 22 according to the amount of solar radiation, by operating the single-phase photovoltaic inverter 22 and the single-phase ESS 23 using the EMS 25 (controller). However, the conventional system 20 has a disadvantage that the EMS 25 (controller), the single-phase photovoltaic inverter 22, and the single-phase ESS 23 have the same software and hardware related to communication, for communication control.
In a case where a single-phase photovoltaic inverter manufactured from ‘A’ company and a single-phase ESS manufactured from ‘B’ company are used, if software and hardware of the single-phase photovoltaic inverter are different from software and hardware of the single-phase ESS, the system 20 shown in FIG. 2 cannot be implemented.